The present invention relates to a hand-operated lever for opening and closing a wedge-type breechblock wherein the opening lever is pivotal about an opener shaft and includes an energy storing element, the operating lever including a transfer apparatus for causing closing movement of the breechblock, the energy storing element when in a rest position of the operating lever being compressed by the transfer apparatus which is in form-locking connection with the opener shaft during the automatic opening of the breechblock, and wherein the energy storing element remains out of operation during manual opening and closing of the breechblock by use of the opening lever.
Such a hand-operated opening lever is disclosed in DE-OS 3,212,522, which corresponds to U.S. Pat. No. 4,569,269. This hand-operated opening lever causes the opener shaft to open and close a wedge-type breechblock that is part of a gun, so as to easily perform a manual opening and closing movement over a small angle of rotation without having to overcome a spring force. After return of the hand-operated opening lever into its rest position, the wedge-type breechblock is automatically caused to be in a blocked position which is secured against movement. This hand-operated opening lever, when in its rest position, permits the automatic performance of the sequence of movements required for operation of the wedge-type breechblock.
In this prior art hand-operated opening lever, a coil spring is used to store the energy which must be expended during the closing process. However, such coil springs have a very steep spring constant or characteristic curve (of force as a function of distance), so that the force required for the closing movement of the wedge-type breechblock is not available at the same high level over an entire closing stroke. Essentially, this steep spring constant or characteristic curve is determined by the limited space available for the opening lever, for example by the space available in the close quarters of the turret of a combat tank, and a proper closing operation of the breechblock is, under certain circumstances, ensured only for relatively light-weight breechblocks, for example for guns having a caliber up to about 105 mm. In contrast thereto, with a larger caliber gun, the weight of the breechblocks increases considerably so that, due to the increased required level of energy expenditure for the closing movement of the wedge-type breechblock in such a larger caliber gun, the space which would be required for the above-described compression spring would not be available in the close quarters of the turret of a combat tank.
Another drawback in the aforementioned prior art hand-operated opening lever is that the exchange of a single compression spring, or for the exchange of a complete hand lever component group, involves considerably high costs, and furthermore, the exchange of the compression spring or the component group is time consuming.